A variety of analog signal processing circuits include a gain stage configured to amplify an input analog signal. For example, switched-capacitor gain circuits are commonly used to provide such amplification. A typical switched-capacitor gain circuit includes an amplifier (e.g., an operational amplifier) and a set of capacitors onto which an input signal sample may be stored. The stored input signal is subsequently amplified and output from the gain circuit. Although contemporary switched-capacitor gain circuits function well in a variety of applications, they do have some drawbacks. For example, the finite gain of the amplifier, flicker noise (sometimes referred to as “1/f noise”), and DC offsets detrimentally affect the achievable accuracy of such circuits.
To compensate for amplifier imperfections that limit the achievable accuracy of switched-capacitor circuits, a technique referred to as correlated-double-sampling has been implemented in some gain circuits. Correlated-double-sampling generally refers to a sampling technique in which the strength of a signal at a node is determined as a difference between the strength of the signal at the node when the signal is coupled to the node and the strength of the signal at the node when the signal is decoupled from the node. Although correlated-double-sampling techniques may improve the achievable accuracy of switched-capacitor circuits, the accuracy improvements come at a cost. More particularly, some prior correlated-double-sampling, switched-capacitor circuits include significantly more circuitry to perform correlated-double-sampling, thus increasing the overall cost and complexity of the gain stage. In addition or alternatively, many prior correlated-double-sampling, switched-capacitor circuits impose limitations on the bandwidth of the input signal that may be processed.